The main objective of this proposal is to develop and deliver a high density continuous perfusion cell microarray to enable high throughput and high quality cell-based screening for the pharmaceutical and biotechnology industry. More specifically, the 6-month Phase I project will focus on developing the core microfluidic cell microarray for high throughput in vitro toxicity screening of human hypatocyte cell lines for better prediction of drug toxicity at an early stage of the drug discovery processes. Taking advantage of the state-of-the-art polymer and semiconductor manufacturing processes, we will create a rigid and robust microfluidic template to reliably copy thousands of replicates. With our demonstrated expertise in microfabrication and the proprietary high aspect ratio soft lithography technology, we will make robust high throughput toxicity analysis readily available in the market. The primary targets of this project are to develop reliable and high yield manufacturing process for high aspect ratio microfluidic devices and to deliver a high density cell microreactor array with binary combinatorial culture and assay functions. [unreadable] [unreadable] [unreadable]